> Then is torture, rape and murder wrong because the victim is sentient, or because the perpetrator is?

Nothing is wrong unless it's done by a moral actor (which is a much higher standard than sentience. Pretty much everything with a central nervous system is sentient, but lobsters, for instance, are not moral actors.

Similarly, the usual understanding of the moral status (the gravity of not the binary permissible/wrong status) of the three acts you describe is somewhat connected to the target as well as the actor being a moral actor (that's least the case with torture, and most the case with murder) rather than merely sentient.

There are arguments to be made for both. Some crimes, even if virtual, can stain or corrupt the perpetrator in ways inimical to society. There are plenty of examples of people who fantasised or role played abhorrent behaviour and went on to perpetrate it in real life, so there is a real danger.

For example we tolerate computer games with virtual killing, but don’t tolerate virtual rape games. Even with virtual killing there are limits. Should we tolerate nazi death camp torturer simulation games?

Because the victim is, of course.